To better endure the implements of harsh weather conditions typically associated with the fall and winter seasons, attempts have been made to develop and utilize electrically-heated apparel in attempts to maintain a more comfortable body temperature. In general, however, most available electrically-heated apparel possess inherent disadvantages that render their use highly inefficient, impractical and problematic.
Specifically, most available electrically-heated apparel are typically heated via a plurality of electrical heating wires woven or coiled throughout the garment, wherein application of a power source (i.e., batteries, AC or DC power sources) to the electrical heating wires causes the wires to produce and release heat. Examples of such devices may be seen with reference to U.S. Pat. No. 2,329,76 to Jacobsen, U.S. Pat. No. 4,404,460 to Kerr, U.S. Pat. No. 5,008,517 to Brekkestran et al. and U.S. Pat. No. 5,032,705 to Batcheller et al. However, utilization of a plurality of segregated electrical heating wires in thermal garments bear obvious disadvantages.
For instance, thermal garments possessing a plurality of segregated electrical heating wires typically hinder flexibility of the garment, restricting or recognizably limiting the wearer's freedom of movement. Furthermore, a plurality of segregated electrical heating wires in garments generally produce a concentrated, localized, and generally non-uniform, dispersion of heat; thus, heating only specific areas or points of the wearer's body. Although the above-referenced U.S. patents have attempted to remedy the non-uniform or localized production of heat generated from electrical heating wires via the incorporation of a plurality of tightly coiled and/or serpentine wire configurations woven throughout the garment, such designs typically result in the aforementioned disadvantageous creation of a restrictive or non-pliable garment.
As a result of the restrictive nature of thermal garments laden with electrical heating wires, much of a wearer's movement within such garments is typically forced. Such forced bodily motions within garments having electrical heating wires have significant bearing on the preservation of wire yield strength, wherein excessive, continuous, general and/or forced movement within the garment results in the heating wires breaking at the stress points where yield strength has been diminished. As such, a break in the electrical heating wire results in safety-related concerns and in the cessation of current past the breakpoint, and thus, the non-heating of the associated area of the garment.
Although some thermal garments that eliminate the need for electrical heating wires as a heat producing means are available, these types of garment also possess clear disadvantages. For instance, U.S. Pat. No. 4,764,665 to Orban et al. discloses electrically heated gloves formed from a woven fabric that is metalized after being formed into the glove structure so as to maximize heat generated by the configuration of the fabric in the glove. The Orban et al. device is, however, disadvantageous, as the woven fabric utilized therein is a conventional textile fabric such as cotton or polyester, which can present significant patent and latent defects when metalized. More specifically, due to the pliability of textile fabrics, a metal coating applied to such fabrics formed into a garment will undergo significant yield and tensile stress when subject to the forces commonly associated with general body movement. As such, areas of the fabric where the yield and/or tensile strength has been diminished will generally result in the cracking and/or flaking of the metal coating, thus creating points of discontinuities in the metalized fabric, wherein such points of discontinuities cause interruptions and/or cessations of electrical current therepast, yielding an unevenly heated thermal garment.
Therefore, it is readily apparent that there is a need for a thermal garment that creates a uniform distribution of heat throughout the surface area of the garment, wherein the thermal garment promotes general bodily movement without diminishing the structural integrity of the fabric.